Toshihiko Matsuo is working as an eye doctor at Okayama University Hospital, Okayama City, Japan. His expertise in ophthalmology covers vitreoretinal surgeries, uveitis, pediatric ophthalmology, eyes in systemic diseases, and ophthalmic neoplastic diseases. He wrote many clinical articles related with his specialties. He also has an appointment in Okayama University Medical School and Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences. His main research ares at present are clinical and basic development of retinal prosthesis and strabismus genetics. Retinal prosthesis is a novel type called Okayama University-type retinal prosthesis (OUReP) which consists of photoelectric dye-coupled thin polyethylene film. Surface electric potential generated in response to light stimulates nearby neurons to induce action potential. The biological safety and surgical safety have been proven, and the efficacy has been proven by its implantation in monkey eyes with macular degeneration. He is now negotiating for an investigator-initiated clinical trial of OUReP with Pharmaceuticals and Medical Devices Agency (PMDA) in Japan. His second research area is genetics of comitant strabismus. Strabismus is a common disease with early onset in childhood. It has genetic background as evidenced by family history and phenotypic concordance between monozygotic twins. From the year 2000, he has been working to identify choromosomal susceptibility loci for comitant strabismus.